This invention relates to a feeder for dispensing various types of materials from a hopper to a place outside the hopper, and particularly to a swing arm feeder. More particularly, this invention relates to a feeder including a swinging ram that is movable in a trough located at the bottom of the hopper to discharge solid waste materials and sludges from the hopper through a discharge outlet.
Sludges and shredded solids are industrial waste materials that are difficult to transport and handle. In many industrial processes, waste sludges and solids are first accumulated in large hoppers and then discharged into smaller containers for delivery to a point of use. For example, disposal of many solid waste materials is accomplished by collecting such materials in a hopper and discharging small batches of such materials into waste incinerators or cement kilns. Advantageously, burning waste in the firing chamber of a cement kiln is economical because the waste material is disposed in an environmentally sound manner and serves as fuel to sustain the burn in the kiln firing chamber.
Delivery of sludges and shredded solids to an incinerator, kiln, or other destination presents a number of significant engineering challenges. Solid wastes can occur in many forms ranging from hard crystalline solids to viscous sticky sludges. They are not easily blended or dispensed.
Conventional feeder mechanisms have not handled sludges and shredded solids particularly well. Conventional screw feeders are limited by an inability to handle stringy materials or materials that tend to cake or build up on the auger provided in the screw feeder to move waste materials. Conventional reciprocating ram feeders often jam in use as a result of waste material build-up behind the ram.
Moreover, waste material "bridging" problems often develop in the hoppers of conventional screw or reciprocating ram feeders because of the tendency of both wet, sticky waste sludges and dry waste solids periodically to form a somewhat horseshoe-shaped arch over the movable auger or ram. This waste material arch is sometimes called a "bridge." Whenever a waste material bridge develops in a hopper above a movable auger, ram, or the like, it acts as a barrier to block other waste material in the hopper from reaching the underlying movable auger, ram, or other discharge mechanism. Unfortunately, conventional feeders can be disabled or impaired by waste material bridging problems.
Recognizing the importance of disposing waste materials in a proper and effective manner, there is a need for a hopper and feed mechanism for waste sludges and solids. Such a mechanism would operate in a manner so as to overcome waste material bridging problems automatically and to mix the waste materials in the hopper continuously. It would further operate to dispense a series of small batches of waste material out of the hopper to a destination such as a container-filling system or the like. A feeder that could meet such demands would represent a substantial improvement over conventional feeders.
According to the present invention, a feeder is provided for discharging a load of material to a place outside the feeder. The feeder includes a hopper, a discharge outlet, and an inclined trough located in a bottom portion of the interior region of the hopper. Various types of materials can be stored in the hopper for later discharge via the inclined trough and the discharge outlet. The inclined trough is formed to include a curved material-receiving channel having a curved floor.
The feeder further includes a ram movable in the curved material-receiving channel and on the curved floor. The ram is movable along this curved path between a raised position away from the discharge outlet and a lowered position adjacent to the discharge outlet. The feeder also includes means for moving the ram on the curved floor from its raised position to its lowered position to discharge a load of material out of the hopper through the discharge outlet to a place outside the feeder.
In preferred embodiments, the moving means includes a pivotable swing arm having a lower end appended to the ram and an upper end mounted on a pivot shaft extending along a front edge of the hopper. Advantageously, the pivoting movement of the swing arm needed to move the ram back and forth between its raised and lowered positions causes the swing arm to slice through the material stored in the hopper. This cyclic slicing movement of the swing arm provides the agitation needed to break up any waste material bridges that may develop and thereby overcome material bridging problems. Also, mixing blades are mountable on the swing arm to facilitate blending of the material in the hopper during pivoting of the swing arm back and forth in the hopper.
Preferably, the inclined trough has a trapezoidal shape and includes first and second inclined side walls. These side walls extend along the curved floor of the material-receiving channel in spaced-apart relation to one another. The side walls are inclined to converge toward the floor to define the trapezoidal shape of the inclined trough. Ideally, the ram includes a body having a matching trapezoidal cross-sectional shape and a curved bottom surface engaging the curved floor of the material-receiving channel. The trapezoidal design of the inclined trough and the ram advantageously enhances the material-discharging capacity of the feeder. This feeder is able to handle discharge of many stringy, sticky, shredded solid waste materials and sludges without frequent jamming.
Illustratively, a valve is provided at the discharge outlet to regulate discharge of material from the hopper. The valve is configured to prevent backflow of material that has been discharged from the material-receiving channel through the discharge outlet back into the material-receiving channel during movement of the ram in the channel from its lowered position to its raised position. Advantageously, the valve does not block or otherwise disrupt discharge of material from the hopper through the discharge outlet.
Although various hopper shapes may be used to enclose the swing arm and provide the required waste material holding capacity, it ideally includes a pair of conical side wall sections arranged to lie in spaced-apart cup-shaped relation on either side of the inclined trough to funnel material in the interior region of the hopper into the trapezoidal, curved material-receiving channel through a top opening in the trough. Illustratively, each conical side wall section is a quarter section of a very short and broad-based cone. This type of hopper shape also helps to control movement of material in the interior region of the hopper toward the trough and prevent material arches or bridges over the trough from forming.
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.